An extra link, based off guruz's link in his Sticky, SourceForge.net: Gtk-Gnutella: gtk-gnutella-users or gtk-gnutella-announcements for more up to date information.

These links in both especially et voilà's post above & guruz's Sticky threads will keep you up to date with new releases. Gtk-Gnutella is still developing, but to see newest releases keep an eye on those pages.